This invention relates to a new process for the preparation of siloxane copolymers and resin compositions containing the siloxane copolymers prepared by the process.
Thermoplastic resins are industrially useful molding materials for plastic containers, film, fiber, adhesives, extruded sheets and the like. Such thermoplastic resins (for example, polycarbonate resin whose main unit is 2,2-bis(4-hydroxyphenyl)propane (bisphenol A)) has excellent mechanical and electric properties, heat resistance, dimensional stability, transparency and moldability. However, such thermoplastic resin has disadvantages in flammability, production of a toxic gas upon burning or the like.
Since thermoplastic resins usually have high flammability, the thermoplastic resin is generally made fire-retardant by adding a fire-retardant, typically a halogen or a phosphorous compound, in the application where fire-retardance is required. However, these fire retardants are not preferred from the environmental viewpoint because they produce a more toxic gas upon burning than the thermoplastic resin itself. Moreover, there are problems in a fire retardant such as that the properties of a thermoplastic resin such as mechanical and electric properties, heat resistance, weatherability or the like may decrease dependent on the amount of it added.
As a means to improve fire retardance and moldability of thermoplastic resins, a method in which a siloxane compound is added to thermoplastic resins has been proposed. However, this method has a problem that fire retardance and moldability may not be sufficient, or the siloxane compound may bleed on the surface of a molded article of a thermoplastic resin when the compatibility of a siloxane compound with a thermoplastic resin is low.
As a means to solve the above-mentioned problems, a technique concerning to a method for producing a siloxane copolymer has been proposed. For example, in Japanese Laid-Open Publication No. 2-196823, Japanese Laid-Open Publication No. 3-106937 and Japanese Laid-Open Publication No. 7-2999, a method for producing a polyestercarbonate-siloxane copolymer by an interfacial polycondensation method using bisphenol derivatives, dicarboxylic acid dichloride, phosgene and phenol terminated dimethylpolysiloxane has been proposed. Moreover, in Japanese Laid-Open Publication No. 5-222173, a method for producing a polyestercarbonate-siloxane copolymer by an interfacial polycondensation method using phenol terminated dimethylpolysiloxane has been proposed. However, in interfacial such polycondensation methods, there are problems that phosgene and acid chloride, which are raw materials, are not easily available, and using a halogen compound such as methylene chloride is not preferred from the environmental viewpoint.
As a means to solve problems in the interfacial polycondensation method, in Japanese Laid-Open Publication No. 4-91125, a method for producing a polyester-siloxane block copolymer by a molten condensation polymerization method using dicarboxylic acid diester, diol and phenol terminated dimethylpolysiloxane has been proposed. However, in this method, because of using an expensive and special silicon compound, there are problems that the production cost is high and when the amount of siloxane unit introduced into the block copolymer increases, the physical properties (for example, mechanical strength) decrease due to a phase separation.
On the other hand, Curry et al have proposed a method for producing a siloxane copolymer to be obtained from a diol and bis(anilino)diphenylsilane (J. Appl. Polym. Sci., vol.9, pp. 295 (1965)). In this method, since the polymer produced becomes an alternating copolymer, it becomes possible to increase the introduced amount of siloxane. However, in this method, because of using an expensive and special silicon compound, the production cost becomes high and further there is a problem that it takes a long time period for the reaction. Also, there is a problem that heat-resistance of the obtained siloxane copolymer is inferior.
The purpose of this invention is to provide a method to overcome the above-mentioned problems existing in the above-mentioned conventional method for producing a siloxane copolymer and to produce a siloxane copolymer having excellent mechanical properties (for example, strength, breaking elongation and impact resistance), heat-resistance, fire-retardance, moldability (for example, mold releasing property, surface lubricating property) and transparency in more easily and more inexpensive (that is industrially and commercially advantageous). Moreover, another purpose of this invention is to provide a resin composition containing siloxane copolymer obtained by the method.
This invention is a process of producing a siloxane copolymer comprising the step of reacting at least one diol, at least one dicarbonate and a silicon compound in the presence of an esterification or transesterification catalyst, wherein said silicon compound is at least one compound selected from the group consisting of compounds represented by the general formulas (I) and (II): 
wherein R1, R2, R3, R4, X and Y are each independently a hydrogen atom, a halogen atom, a hydroxide group, an amino group or a substituted or non-substituted organic group; a represents an integer from 0 to 5000 and b represents an integer from 3 to 20.
In a preferred embodiment, the above-mentioned diol is represented by the following general formula (III):
HOxe2x80x94R5xe2x80x94OH xe2x80x83xe2x80x83(III) 
wherein R5 is a bivalent hydrocarbon group having 1 to 20 carbon atoms wherein at least some of the hydrogen atoms in the hydrocarbon group may be substituted with at least one group selected from a halogen atom, a hydrocarbon group, an alkoxy group and a phenoxy group; or xe2x80x94R6xe2x80x94Axe2x80x94R7xe2x80x94, wherein R6 and R7 are each independently a bivalent aromatic hydrocarbon group having 6 to 20 carbon atoms; and A is selected from the group consisting of a single bond, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SOxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94COxe2x80x94 and a bivalent hydrocarbon group containing 1 to 20 carbon atoms.
In a preferred embodiment, the process further comprises the step of reacting at least one diester of a dicarboxylic acid. The diester of a dicarboxylic acid is represented by the following general formula (IV): 
wherein R8 is a bivalent hydrocarbon group having 1 to 20 carbon atoms wherein at least some of the hydrogen atoms in the hydrocarbon group may be substituted with at least one group selected from a halogen atom, a hydrocarbon group, an alkoxy group and a phenoxy group; or xe2x80x94R10xe2x80x94Dxe2x80x94R11xe2x80x94, and R9 is a hydrocarbon group having 1 to 20 carbon atoms, wherein R10 and R11 are each independently a bivalent aromatic hydrocarbon group having 6 to 20 carbon atoms; and D is selected from the group consisting of a single bond, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SOxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94COxe2x80x94 and a bivalent hydrocarbon group having 1 to 20 carbon atoms.
In a preferred embodiment, the above-mentioned dicarbonate is represented by the following general formula (V): 
wherein R12 represents a hydrocarbon group having 1 to 20 carbon atoms.
In a preferred embodiment, the above-mentioned silicon compound is at least one selected from the group consisting of polydimethylsiloxane, polymethylphenylsiloxane, dimethoxydimethylsilane, dimethoxydiphenylsilane, octamethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane.
In a preferred embodiment, the above-mentioned diol is at least one selected from the group consisting of 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, bis(4-hydroxyphenyl)sulfone, 9,9-bis(4-hydroxyphenyl)fluorene.
In a preferred embodiment, the above-mentioned diester of dicarboxylic acid is at least one selected from the group consisting of diphenylterephthalate, diphenylisophthalate, dimethylterephthalate and dimethylisophthalate.
In a preferred embodiment, the above-mentioned dicarbonate is diphenylcarbonate.
In a preferred embodiment, the above-mentioned esterification or transesterification catalyst is tin compound.
In a preferred embodiment, the above-mentioned esterification or transesterification catalyst is at least one selected from the group consisting of an acetate, a carbonate, a borate, an oxide, a hydroxide, a hydride, an alcholate and a phenolate of a metal selected from the group consisting of lithium, sodium, potassium, magnesium, calcium, barium, strontium zinc, cadmium, titanium, zirconium, antimony, lead, manganese or cobalt.
In a preferred embodiment, the above-mentioned esterification or transesterification catalyst is used in the range of 0.0001 to 1.0 parts by weight based on 100 parts by weight of the siloxane copolymer obtained.
Moreover, this invention relates to a fire retardant resin composition containing the siloxane copolymer obtained by the above-mentioned process.
Moreover, this invention relates to a resin composition for molding containing the siloxane copolymer obtained by the above-mentioned process.